TypeScript three.8, a new version of Microsoft’s typed superset of JavaScript, is now obtainable as a creation release. The latest TypeScript upgrade emphasizes kind-only imports and exports and ECMAScript specifications compliance.
The release provides a new syntax for kind-only imports and exports, with the intent of providing buyers much more great-grained management around import and elision. The import kind syntax only imports declarations to be employed for kind annotations and declarations and often gets entirely erased. The export kind syntax only presents an export to be employed for kind contexts and is erased from TypeScript output.
TypeScript has employed JavaScript’s import syntax to enable reference varieties. Whilst hassle-free, the capacity only worked because of the import elision element, which omits TypeScript kind imports when TypeScript outputs JavaScript documents. Even so, import elision has been both insufficient and problematic.
In conjunction with import kind, TypeScript three.8 also provides a compiler flag to management what occurs with imports that will not be employed at runtime: importsNotUsedAsValues.
With regards to the ECMAScript conventional for JavaScript, TypeScript three.8 provides help for ECMAScript private fields, which is element of a course fields declaration proposal for JavaScript. Public and private fields will be built-in into single, orthogonal entire, in accordance to this proposal.
Other advancements promised in TypeScript three.8 involve:
- “Fast and loose” incremental kind-checking, showcasing a compiler option,
assumeChangesOnlyAffectDirectDependencies. This option can decrease create situations in sure documents, as TypeScript will recheck/rebuild only documents that have modified as well as documents that directly import them. It is advisable for substantial code bases where by developers are eager to defer full venture errors till a later time. - Implementation of the export as
* nssyntax, giving a single entry position to expose all customers of another module as a single member. - Leading-amount
await, an future ECMAScript element to take away restrictions on using anawaitexpression at the major of a file below distinct situations. - JavaScript documents are supported in TypeScript three.8 by turning on the
allowJsflag kind-checking of all those documents is supported by means of thecheckjsoption or by adding a // @ts-verify comment to the major of .js documents. New JSDoc tags are leveraged for attributes, because JavaScript documents absence a committed syntax for kind-checking. - A
watchOptionsindustry intsconfig.jsonandjsconfig.jsonlets buyers explain to the compiler/language company which file observing methods to use to maintain track of documents and directories. - A refactoring to convert string concatenations.
- Stricter assignability checks to unions with index signatures, a breaking improve.
- In another breaking improve,
itemin JSDoc is no for a longer periodanybelownoImplicitAny.
You can set up the normal release of TypeScript three.8 as a result of NuGet or by means of NPM:
npm set up typescript